I'd say any trailer repair place or brake shop should be able to to the jobs, I have mechanical disk brakes on my trialer and used to have to change the pads every 6 months due to the rust swelling till the things locked up, last time I did it I used a heavy zink metal primer 2 coats and 2 finish coats of rust guard, paint all but the contact to disk surface, they have lasted for about 2 years. cheers